U.S. Pat. No. 4,065,204, to Morton S. Lipkins, discloses a lateral transfer retroreflector which can be precisely adjusted so that an incoming ray is reflected laterally through an offset distance and then reversely, parallel to the incoming ray. The apparatus includes a base, a roof reflector having two reflecting plates and a third reflector.
U.S Pat. No. 3,936,194, also to Morton S. Lipkins, discloses a method and device for assembling and aligning hollow retroreflectors. The teaching therein is especially applicable to hollow lateral transfer retroreflectors.
While the structure set forth in U.S. Pat. No. 4,065,204 provides an apparatus which can be adjusted for high precision, in that the reflected beam is parallel to the incoming beam to a high degree of accuracy, the reflectors are secured to one another and to the base member along the entire length of edges and marginal surfaces thereof. Thus, extreme variations in temperature tend to introduce stresses which can distort the optical surfaces or have a detrimental effect upon their relative alignment, thus causing accuracy to suffer.